1. Field of the Invention
The present invention relates in general to an electroluminiescent (EL) lighting, and more specifically, to illuminating a keypad of a remote vehicle entry transmitter.
2. Description of the Related Art
Remote vehicle entry transmitters are used for performing a wireless operation on a vehicle such as locking and unlocking a door, unlatching a trunk latch, or activating or deactivating an alarm system equipped on the vehicle. These remote entry devices are commonly referred to a remote keyless entry (RKE) fob. The RKE fob is carried with the operator of a vehicle and can wirelessly perform these functions when within a predetermined reception range of the vehicle. The RKE fob is typically a small rectangular or oval plastic housing with a plurality of depressible buttons for activating each one of the wireless operations. The outer surface of the housing is typically black in color. Each button is also typically black with a graphical display printed each of the buttons. The graphical display is commonly white or red. While these graphical displays are easily visible the daylight, they are not so easily visible during night hours in less ambient light. During the nighttime in poorly lit or no light conditions, the operator carrying the RKE fob must either have to recall the location of the each button on the RKE fob or press each button by trial and error until the appropriate button is depressed activating the intended function.
To assist the operator in viewing the buttons of the RKE fob during poor lighting conditions, lighting schemes may be added to the RKE fob for illumination purposes, however the packaging of lighting elements in the RKE fob are limited due to size and packaging constraints. LEDs typically used for backlighting, such as in phones, are small in size, however, LEDs must be properly positioned to illuminate more than one button or incorporate light piping to tunnel the light to the plurality of buttons. An individual LED used to illuminate more than one button often produces uneven distribution of lighting on each button.
Electroluminescence (EL) lighting uses an EL film that is excited by a high voltage source to produce an even distribution of lighting throughout the film. Keypads made with EL film may be inserted through fascia button holes for illumination, however, this creates separate and distinct components within the RKE fob and may be subject to misalignments when assembled. Stack-up and dimensional tolerancing issues are potential manufacturing problems when a first component is inserted into a second component. For example, a separate keypad having a plurality of buttons inserted into a fascia having a plurality of apertures to receive the plurality of buttons may result in misalignments due to dimensional tolerances of the two separately molded components.